The Royal Institute of Technology is a university in Stockholm, Sweden. KTH was founded in 1827 as Sweden's first polytechnic and is one of Scandinavia's largest institutions of higher education in technology. KTH accounts for one-third of Sweden's technical research and engineering education capacity at university level. KTH offers programmes leading to a Master of Architecture, Master of Science in Engineering, Bachelor of Science in Engineering, Bachelor of Science, Master of Science, licentiate or doctoral degree. The university also offers a technical preparatory programme for non-scientists and further education.There are a total of just over 14 000 full-year equivalent undergraduate students, more than 1700 active postgraduate students and 4600 full-time-equivalent employees. KTH is one of the leading technical universities in Europe and highly respected worldwide, especially in the domains of technology and natural science. Wikipedia.
News Article | May 18, 2017
The strongest yet hybrid silk fibers have been created by scientists in Sweden using all renewable resources. Combining spider silk proteins with nanocellulose from wood, the process offers a low-cost and scalable way to make bioactive materials for a wide range of medical uses. Published in American Chemical Society Nano by researchers from KTH Royal Institute of Technology in Stockholm, the technique brings together the structural and mechanical performance of inexpensive cellulose nanofibrils with the medicinal properties of spider silk, which is difficult and expensive to fabricate on a larger scale. The bioactive properties of spider silk have been known for centuries. In ancient Rome, spider webs were used to dress soldiers’ battle wounds. But producing large scale amounts of spider silk material today has proven an expensive process, which often relies on fossil-based sources. KTH Protein Technology researcher My Hedhammar says that by comparison, wood-based nanocellulose is cheap and sustainable. Furthermore, the technique of combining it with only small amounts of spider silk protein yields a biofunctional material that can be used for such medical purposes as promoting cell growth.
News Article | May 25, 2017
In some businesses -- like supermarkets and restaurants -- local restrictions on nighttime deliveries leave distributors no choice but to dispatch trucks during morning rush hours. But lifting these rules could reduce peak traffic volumes and increase transport efficiency, according to a recent study involving researchers from KTH Royal Institute of Technology in Stockholm. Some communities prohibit heavy trucks from operating during the night. Stockholm is one of them, but the city wanted to test if lifting its ban might yield some benefits in transportation efficiency. Anna Pernestål Brenden, a researcher at KTH's Integrated Transport Research Laboratory, and acoustic, transport efficiency, and policy researchers from the KTH, joined with other partners in a pilot study with the City of Stockholm to see if lifting the 10 to 6 a.m. ban on truck deliveries made sense. They worked with a national supermarket chain and its suburban Stockholm central warehouse, as well as with a company that supplied food to restaurants and hotels, Pernestål Brenden says. Ordinarily the supermarket warehouse, which is some 30km north of Stockholm, would deploy several fully-loaded trucks to make deliveries during peak morning rush hours from 6 to 8, because there is no way for one truck to make them all in that short a time span. But in the study, a single truck delivered goods to three stores in central Stockholm between the prohibited hours of 10 p.m. and 6 a.m. It would return to the warehouse three times in the night to be reloaded, and then make its subsequent delivery, she says. "That's one truck doing the work of three, or in other words -- morning commuters are spared having to share the road with three heavy duty trucks." Though it was a small scale study, Pernestål Brenden says there are strong indications that scaling up off-peak deliveries could increase business efficiency for suppliers and retailers, reduce fuel consumption and CO2 emissions and perhaps make a positive impact on traffic volume during peak morning hours. But part of the study was also to assess whether deliveries at night bothered neighbors. The drivers had to follow some rules: for example, no using reverse signals or talking on cell phones outside the vehicle. Also, two trucks equipped with low noise technology were used. "It turned out that the noise people complained about was caused mainly by unloading the truck, not driving," she says. KTH acoustics researchers created a sound recording system that placed microphones in the front and back of the truck. The front microphones would record when the truck was getting unloaded, so that neighborhood background noise could also be taken into account. The system allowed researchers to evaluate the mix of sound from both vehicle and environment and give a true picture of what difference the unloading of the vehicle actually made. One particularly quiet neighborhood on the edge of the city was the source of complaints from neighbors -- but Pernestål Brenden says the results show most people don't notice the unloading in neighborhoods with sufficient background noise. "Only in the quiet neighborhoods does noise raise a problem," she says. The study also involved truck manufacturers Scania and Volvo, as well as goods owners, carriers, goods receivers, and companies that make silent roller cage. KTH was also asked to validate new technologies, such as a zone management concept for electric hybrid vehicles. Pernestål Brenden explains that this system would automatically switch the engine to electric, rather than diesel, power in certain geographic zones. She describes the study as a "small step" for more efficient transport. "By making small changes we can improve transport efficiency, reduce congestion, and enable new business models for goods receivers," she says.
News Article | April 21, 2017
Researchers in Sweden have discovered a new way to filter water off-grid using wood fibers. The team from KTH Royal Institute of Technology hope that it can provide clean water to people in refugee camps and in remote areas. The researchers developed a new material using wood fibers and a positively-charged polymer that can bind bacteria to its surface, which removes the bacteria from the water, leaving it purified. The material could also be used in bandages to prevent infection, plasters and in packaging. "Our aim is that we can provide the filter for a portable system that doesn't need electricity – just gravity – to run raw water through it," said Anna Ottenhall, a PhD student at KTH's School of Chemical Science and Engineering. "The great idea is that we are trapping the bacteria and removing them from the water by our positively-charged filter. The bacteria trapping material does not leach any toxic chemicals into the water, as many other on-site purification methods do." The material works because the positively-charged polymer attracts bacteria and viruses which are negatively charged. The bacteria are then stuck to the surface and cannot break free or reproduce and they ultimately die. This technique means no chemicals or antibacterial agents are needed and it also doesn't produce any bacterial resistance. After the wood filter has been used, it can then be safely burned. This is just one of many wood fiber innovations. They've been tapped for use in eco-friendly batteries and solar cells as well. The natural material could mean cheaper and safer technologies in variety of applications.
News Article | May 3, 2017
As a commodity, the least valuable part of the wheat grain is the bran – the outer coating of the kernel, which is typically sold as animal feed. Now researchers at KTH Royal Institute of Technology in Stockholm have developed a process to extract valuable biomolecules from this offal which could be used as antioxidants, prebiotics and even food packaging material. The extraction process uses only hot, high pressure water and carbohydrate-active enzymes to harvest wheat bran's hemicelluloses and oligosaccharides. This process allows these polysaccharides to retain their antioxidant properties – which are stripped away through ordinary alkaline extraction techniques. Andrea Ruthes, postdoctoral researcher, and Francisco Vilaplana, associate professor in Glycoscience at KTH Royal Institute of Technology are the scientists behind this discovery, which was reported in the recent issue of the journal Green Chemistry. "In bran and other cereal tissues, the hemicelluloses are difficult to extract because they're tighly interconnected and recalcitrant," Vilaplana says. One way to do it is with alkaline, but that also destroys the part of the molecule that gives it its antioxidant functions. "We use a cascade approach where we first extract the hemicelluloses in polymer form and then we use the enzymes to selectively tackle the un-extractable residue. In this way we maximize total yields of valuable biomolecules from the bran," he says. Vilaplana says his research group is studying possible applications for these biopolymers, including active food packaging films and thickeners that provide a natural, non-additive way to prevent oxidation. In medicine, they could also be used to encapsulate oxygen-sensitive active compounds and to reduce the inflammation caused by reactive oxygen species (ROS) in biomedical applications. The hemicelluloses and oligosaccharides are also well-known to have prebiotic properties as dietary fibres, which are important for improved nutrition and human health. "Our process could contribute over the long term to use of cereal hemicelluloses with antioxidant activities in many ways, such as non-fossil based packaging, preserving sensitive foods or drugs from oxidation, dietary fibre supplements and texturizing gels in food and cosmetic products. Explore further: Engineering wheat arabinoxylan for new applications More information: Andrea C. Ruthes et al. Sequential fractionation of feruloylated hemicelluloses and oligosaccharides from wheat bran using subcritical water and xylanolytic enzymes, Green Chem. (2017). DOI: 10.1039/C6GC03473J
Gouteraux B.,KTH Royal Institute of Technology
Journal of High Energy Physics | Year: 2014
In this work, we examine how charge is transported in a theory where momentum is relaxed by spatially dependent, massless scalars. We analyze the possible IR phases in terms of various scaling exponents and the (ir)relevance of operators in the IR effective holographic theory with a dilaton. We compute the (finite) resistivity and encounter broad families of (in)coherent metals and insulators, characterized by universal scaling behaviour. The optical conductivity at zero temperature and low frequencies exhibits power tails which can violate scaling symmetries, due to the running of the dilaton. At low temperatures, our model captures features of random-field disorder. © The Authors.
Miao G.,KTH Royal Institute of Technology
IEEE Transactions on Wireless Communications | Year: 2013
This paper addresses optimal energy-efficient design for uplink (UL) MU-MIMO in a single cell environment. The energy efficiency is measured by throughput per Joule, while both RF transmission power and device electronic circuit power are considered. We define the energy efficiency (EE) capacity for UL MU-MIMO and study the power allocation that achieves this capacity. First we assume all users consume a fixed amount of circuit power and show that user antennas should be used only when the corresponding spatial channels are sufficiently good and using them improves the overall network EE. Mobile devices may have improved circuit management capability and turn off circuit operations when some antennas are not used to reduce circuit power consumption. Therefore we further study energy-efficient UL MU-MIMO with improved circuit management and show that some antennas should not be used even when their channel states are good because turning them on consumes too much circuit power. Based on theoretical analysis, we further develop low-complexity yet globally optimal energy-efficient power allocation algorithms that converge to the optimum exponentially. Simulation results are provided to demonstrate the significant gain in network energy efficiency. © 2002-2012 IEEE.
Moberg C.,KTH Royal Institute of Technology
Angewandte Chemie - International Edition | Year: 2013
Two views: The mechanism of the conjugate addition of linear aldehydes to nitro olefins has been investigated by two research groups. In spite of extensive experimental data, important questions remain unanswered (see scheme; TMS=trimethylsilyl, En=enamine). Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Walter M.V.,KTH Royal Institute of Technology |
Malkoch M.,KTH Royal Institute of Technology
Chemical Society Reviews | Year: 2012
Dendrimers are highly branched and monodisperse macromolecules that display an exact and large number of functional groups distributed with unprecedented control on the dendritic framework. Based on their globular structure, compared to linear polymers of the same molecular weight, dendrimers are foreseen to deliver extraordinary features for applications in areas such as cancer therapy, biosensors for diagnostics and light harvesting scaffolds. Of the large number of reports on dendrimer synthesis only a few have reached commercial availability. This limitation can be traced back to challenges in the synthetic paths including a large number of reaction steps required to obtain dendritic structures with desired features. Along with an increased number of reaction steps come not only increased waste of chemical and valuable starting materials but also an increased probability to introduce structural defects in the dendritic framework. This tutorial review briefly covers traditional growth approaches to dendrimers and mainly highlights accelerated approaches to dendrimers. A special focus capitalizes on the impact of the click chemistry concept on dendrimer synthesis and the promise it has to successfully accomplish highly sophisticated dendrimers, both traditional as well as heterofunctional, in a minimum number of chemical steps. It is clear that accelerated synthetic approaches are of greatest importance as these will encourage the scientific community to synthesize and access dendrimers for specific applications. The final goal of accelerated synthesis is to deliver economically justified dendritic materials for future applications without compromising the environmental perspective. © 2012 The Royal Society of Chemistry.
Aronson M.F.,KTH Royal Institute of Technology
Proceedings. Biological sciences / The Royal Society | Year: 2014
Urbanization contributes to the loss of the world's biodiversity and the homogenization of its biota. However, comparative studies of urban biodiversity leading to robust generalities of the status and drivers of biodiversity in cities at the global scale are lacking. Here, we compiled the largest global dataset to date of two diverse taxa in cities: birds (54 cities) and plants (110 cities). We found that the majority of urban bird and plant species are native in the world's cities. Few plants and birds are cosmopolitan, the most common being Columba livia and Poa annua. The density of bird and plant species (the number of species per km(2)) has declined substantially: only 8% of native bird and 25% of native plant species are currently present compared with estimates of non-urban density of species. The current density of species in cities and the loss in density of species was best explained by anthropogenic features (landcover, city age) rather than by non-anthropogenic factors (geography, climate, topography). As urbanization continues to expand, efforts directed towards the conservation of intact vegetation within urban landscapes could support higher concentrations of both bird and plant species. Despite declines in the density of species, cities still retain endemic native species, thus providing opportunities for regional and global biodiversity conservation, restoration and education.
Moberg C.,KTH Royal Institute of Technology
Angewandte Chemie - International Edition | Year: 2011
Same difference: Berry pseutorotation (BPR) and Ugi turnstile rotation, which are generally treated as two distinctly different mechanisms for rearrangement of trigonal-bipyramidal structures, have been shown to be equivalent. Alternative mechanisms consist of sequences of pseudorotations proceeding in a single step. Copyright © 2011 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.